The purpose of this study is to show that abiraterone acetate plus prednisone added to the current standard of care, gonadotropin-releasing hormone (GnRH) decreases prostate specific antigen (PSA) and prolongs the time until it is evident that the cancer has grown. Additionally, safety information about abiraterone acetate in combination with prednisone will be collected. This will include looking at what side effects occur, how often they occur, and for how long they last.

Percentage of Participants With Greater Than or Equal to (>=) 50 Percent (%) Reduction in Prostate-Specific Antigen (PSA) During the Core Study [ Time Frame: End of core study visit (Approximately at Month 6) ] [ Designated as safety issue: No ]

Percentage of participants with greater than or equal to 50 percent decrease in PSA levels was assessed.

Secondary Outcome Measures:

Time to Radiographic Evidence of Disease Progression (TTRP) [ Time Frame: Maximum up to Month 30.5 ] [ Designated as safety issue: No ]

Time to radiographic evidence of disease progression is defined as the time interval from the date of enrollment (Day 1) to the date of disease progression. A participant was considered as progressed by bone scan if: 1) The appearance of greater than or equal to (>=) 2 new lesions, and, following the first assessment, a confirmatory scan performed 6 or more weeks later that shows a minimum of 2 or more additional new lesions, 2) If >=2 new lesions are seen on scans following the first assessment, the confirmation is still required after 6 weeks; however, 2 addition lesions are not required to confirm progression, and 3) The date of progression is the date of the first scan that shows the changes.

Time to Prostate-Specific Antigen (PSA) Progression [ Time Frame: Maximum up to Month 30.5 ] [ Designated as safety issue: No ]

Time to PSA progression is defined as the time interval from the date of enrollment (Day 1) to the date of first evidence of PSA progression. A participant was considered to have a PSA progression if the PSA level had a 25 percent (%) or greater increase and an absolute increase of 2 nanogram (ng)/milliliter (mL) or more, which is confirmed by a second value obtained in 3 or more weeks.

Percentage of Participants With Greater Than or Equal to (>=) 50 Percent (%) Reduction in Prostate-Specific Antigen (PSA) Levels After 3 Cycles of Treatment [ Time Frame: End of Cycle 3 (Approximately Month 3) ] [ Designated as safety issue: No ]

Percentage of participants with greater than or equal to 50 percent decrease in PSA levels was assessed. Decrease in PSA levels represented improvement.

abiraterone acetate in combination with prednisone Abiraterone acetate will be taken as 4 x 250 mg tablets by mouth (PO) once daily. Prednisone will be taken as 2 x 2.5 mg tablets PO once daily.

Drug: abiraterone acetate in combination with prednisone

Abiraterone acetate will be taken as 4 x 250 mg tablets by mouth (PO) once daily. Prednisone will be taken as 2 x 2.5 mg tablets PO once daily.

Detailed Description:

This is a Phase 2, prospective, multicenter, open-label, single-arm study of abiraterone acetate plus prednisone in men with non-metastatic, castration-resistant prostate cancer (CRPC) who have a rising PSA despite castrate levels of testosterone. The study consists of Screening Phase (up to 4 weeks), Core Study Treatment Phase (comprised of six 28-day cycles), Pre-metastatic Disease Follow-up Phase and an optional Post-metastatic Disease Follow-up Phase. Each treatment cycle will last 28 days. Participating subjects will receive study agents (Abiraterone acetate 1000 mg/day plus prednisone 5 mg/day, orally) continually during the study. Subjects who have not had radiographic confirmed disease progression after the Core Study Treatment Phase will continue the study treatment in the Pre-metastatic Disease Follow-up Phase. When disease progression is confirmed, subjects will have an option to continue the study treatment and are able to receive subsequent anti- cancer therapy as clinically needed in Post-metastatic Disease Follow-up Phase. The study will end when all participated subjects have disease progression. Subjects will be required to return to the study site 30 days after receiving the last dose of abiraterone acetate for safety follow-up.

Eligibility

Ages Eligible for Study:

18 Years and older

Genders Eligible for Study:

Male

Accepts Healthy Volunteers:

No

Criteria

Major Inclusion Criteria:

Be a male >= 18 years of age

Have adenocarcinoma of the prostate

Currently receiving continuous treatment with Gonadotropin-releasing hormone (GnRH) monotherapy for at least 6 months before or have undergone surgical removal of the testicles

Serum testosterone of < 50 ng/dL(< 2.0 nM)

Have rising PSA defined as a PSA of ≥ 10 ng/mL obtained at screening or PSADT of ≤ 10 months with the first of the 3 consecutive PSA values used to calculate PSADT ≥ 2.0 ng/mL

Have an Eastern Cooperative Oncology Group (ECOG) performance status less than or equal to 2

Be capable of swallowing study agents whole as a tablet

Be willing/able to adhere to the prohibitions and restrictions specified in this protocol

Major Exclusion Criteria:

Have prior or current evidence of local disease progression or metastatic disease as defined by modified response evaluation criteria in solid tumors (RECIST) criteria

Have received chemotherapy for treatment of castrate-resistant prostate cancer; however, if a patient received chemotherapy in an adjuvant setting, prior to having CRPC, for castrate-sensitive prostate cancer, the patient is still eligible

Are currently receiving any antiandrogen therapy (eg, bicalutamide, flutamide, or nilutamide).

If previously treated with antiandrogen therapy, there must be documentation of at least 2 consecutive rising PSA values at least 2 weeks apart obtained prior to screening

If previously treated with flutamide, at least 1 of the PSA values must be obtained 4 weeks or more after flutamide discontinuation.

If previously treated with bicalutamide or nilutamide, at least 1 of the PSA values must be obtained 6 weeks or more after antiandrogen discontinuation

Have previously received agents having any CYP17 inhibitory activity for the treatment of prostate cancer, such as ketoconazole

Have previously received aminoglutethimide

Have an active infection or other medical condition that would contraindicate prednisone use

Have uncontrolled hypertension

Have active hepatitis or chronic liver disease

Have clinically significant heart disease

Have poorly controlled diabetes

Have received an investigational therapeutic within 30 days of screening

Have partners of childbearing potential and are not willing to use a method of birth control with adequate barrier protection as determined to be acceptable by the principal investigator and sponsor during the study and for 1 week after last dose of abiraterone acetate.

Individuals with a history of a non-prostate malignancy are ineligible for this study with the following exceptions. Individuals with a history of other malignancies are eligible if they have been disease-free for at least 3 years and are deemed by the investigator to be at low risk for recurrence of that malignancy. Individuals with the following cancers are eligible if diagnosed and treated within the past 3 years: basal cell or squamous cell carcinoma of the skin

Contacts and Locations

Choosing to participate in a study is an important personal decision. Talk with your doctor and family members or friends about deciding to join a study.
To learn more about this study, you or your doctor may contact the study research staff using the Contacts provided below.
For general information, see Learn About Clinical Studies.

Please refer to this study by its ClinicalTrials.gov identifier: NCT01314118